Open Clusters in Canis Major and Puppis

6 March 2021, 19:30 – 21:30

Seeing: Average

Transparency: Poor / average

A bitingly cold, breezy evening with plenty of large low clouds scudding from northeast to southwest. Some fireworks were going off in the local park while I was setting up; I assume they were for someone’s birthday or anniversary, as I can’t think of anything else (on a national level) worth celebrating at the moment.

As I was uncertain how much observing time the clouds were going to allow me, I stuck to one eyepiece (the 13mm Ethos at 92x) for the entire session. The conditions weren’t great and my eyes weren’t properly “tuned in” for viewing faint objects (like any skill, averted vision can get rusty if you haven’t used it for a while), but it was a relief to do some actual deep sky observing again after what seemed like an eternity. On another plus note, I tightened up the azimuth bolt and the milk washer trick has worked – the scope turned like a dream, with no stiction. I’m not sure how long it will stay like that, but it’s a cheap and relatively easy fix.

After warming up with a look at the Orion Nebula (because it would feel like a crime not to, when you’ve got an Ethos in your scope), it was over to the other side of the sky to mop up some galaxies in Camelopardalis and Ursa Major.

NGC 2655, galaxy, Camelopardalis

Large round blur with a bright core surrounding a stellar nucleus. The PSA plots another galaxy (NGC 2715) nearby, but I wasn’t able to see it on this occasion.

More clouds obscured the view while I was looking for NGC 2366, so I was forced to relocate back to the far southern reaches of the sky, and an old favourite:

NGC 2362, Tau Canis Majoris cluster (Caldwell 64), Canis Major

Stunning as always; there’s no other cluster quite like it. Not much I can add to previous descriptions, but tonight the seeing steadied enough to show two faint companions east of Tau.

h3945, double star, Canis Major

Beautiful golden primary and duck-egg blue secondary. Another highlight I couldn't resist coming back to.

NGC 2367, open cluster, Canis Major

Small, triangular cluster with about a dozen stars visible.

NGC 2384, open cluster, Canis Major

Small, sparse cluster with meandering trail of stars to the northeast.

NGC 2421, open cluster, Puppis

Rich spray of faint stars. Averted vision suggests underlying haze on the brink of resolving into even more stars.

Another cloud pushed me south again, and while in the area I noticed an interesting asterism south of 3 Puppis which looked like a loose open cluster, but wasn’t marked as such in the atlas. Also, to the north, a beautiful bright double star (k Puppis) comprised of twin white stars. (If h3945 is the winter Albireo, this looked like the winter Gamma Arietis).

M93, open cluster, Puppis

Lovely, rich cluster which looked a bit like a butterfly tonight (brighter stars in the western wing). Two prominent red giant stars on the southern edge of the cluster.

NGC 2482, open cluster, Puppis

Sprinkling of medium-bright to faint stars; larger and looser than M93. Appeared to be an isolated knot of stars of the eastern side of the cluster. My initial impression was favourable, but this cluster seemed to get less impressive the longer I looked at it. (With hindsight, it’s possible there could have been a very thin layer of cloud passing slowly across it.)

NGC 2489, open cluster, Puppis

Small haze sprinkled with faint stars. Just north of three distinctive field stars. I didn’t spot it straightaway, but it is somewhat low in the sky.

With another cloud starting to creep across, I pushed north again and (thanks to the silky-smooth azimuth motion) I swung the scope back and forth between M46 and M47, comparing the two clusters. Photographs tend to bloat out the stars and perhaps make them seem more alike than they really are, but visually the difference between the very bright stars of M47 and the fainter but more homogenous stars of M46 was striking. Planetary nebula NGC 2438 on the northern edge of M46 was not quite as prominent tonight as previous viewings, but still obvious.

More clouds pushed me out of this part of the sky, so I resumed the galaxy hunt.

NGC 3198, galaxy, Ursa Major

Faint streak of light, brighter towards the centre with averted vision. Field star off the northwest edge.

Yet another cloud pushed me south to look for NGC 3432 in Leo Minor, but I couldn’t see anything on this occasion. At this point I realised I was fighting a losing battle (with the cold as well as the clouds), so I finished up with quick visits to NGC 2903, the Leo Triplet, and M81/M82 (including NGC 3077 and NGC 2976). None of them were looking anywhere near their best, so I called it a night.

Nature note:

The garden was quiet tonight; the frogs appear to have concluded their “business”, leaving one third of the pond full of frogspawn.

Canis and Ursa (Major)

12 January 2021, 22:00 – 23:15

Cold, but not as brutal as Saturday. Hazy sky, with bands of cloud waxing and waning in the southwest like a poor man’s aurora. Light condensation on scope.

Seeing: Poor

Transparency: Poor

Given the conditions, and the prospect of cloud ending the session at any moment, I stuck to old (and bright) favourites once again.


Sirius, The Dog Star, Canis Major

171x and 240x. Having recently read that the white dwarf star Sirius B is close to its maximum separation from the primary, roughly 11” east-northeast (following), I wanted to see if I could detect it with my scope. Unfortunately the indifferent seeing quickly put paid to that idea (even Rigel was tough to split tonight), but definitely one to try again if and when conditions allow.

Betelgeuse, Orion

171x. Now looking much more like its old self after last year’s dimming event. A grand view in the DeLite; the orange colour also seemed more intense than last year.

NGC 2392, Eskimo Nebula, Gemini

240x and 133x. Same puffball appearance as Saturday night. Still difficult to make out the shell structure, but the central star was showing well. No colour discernable.


With the clouds starting to interfere I was forced to relocate to the other side of the sky, and with no time to waste consulting star charts, the M81/M82 group was the obvious choice. (At least I can see these galaxies in the finder – just.)


M82, galaxy, Ursa Major

133x. Tapered streak of light (like a candle burning at both ends). Mottling and dark lane visible with averted vision, but nowhere near its best tonight.

NGC 3077, galaxy, Ursa Major

133x. Faint, but obvious. Condensed core with averted vision. It still embarrasses me that I never saw this galaxy before March of last year.

M81, galaxy, Ursa Major

133x. Bright core with stellar nucleus. Ill-defined outer haze; I reckon the spiral structure might be visible in the Ethos on a really good night when M81 is near maximum elevation. Dark patches near core were just about visible. Something else I hadn’t paid enough attention to before tonight: the two close foreground double stars in a line southwest from the core; the outermost pair just barely split at 133x.

And so, with the clouds closing in, that was it for the session.

The Tao of Tau Canis Majoris

28 January 2020, 21:30 – 23:30

A cold, breezy night. My feet felt frozen by the end of the session despite two layers of socks. Some hazy bands of cloud moving slowly from the south-west from about 23:15 onwards. But no condensation for a change.

Seeing: Average
Transparency: Good to Average

I started with a tour of some old favourites using the Panoptic 24mm (50x), before switching to higher magnification once the scope had cooled to ambient temperature and my eyes had dark-adjusted.

M42, The Orion Nebula
Viewed at 50x and 133x, both with and without the OIII filter. Not much I can add to previous descriptions; with the filter in place the nebulosity almost overwhelmed the Trapezium, particularly at the lower magnification. The OIII also imparted a strong green colour, more so than any other object I’ve used it on.

NGC 2392, Eskimo Nebula, Gemini
Showed up nicely at 92x (13mm Ethos). Bright shell and central star seen with direct vision; double shell with averted vision. Pale blue colour.

NGC 2420, open cluster, Gemini
At 92x appeared as a condensed fuzz of stars, about a dozen resolved with direct vision – more with averted vision. Lines of stars appear to curl out to four “corner” stars, giving the cluster a shape resembling a Mermaid’s Purse.

NGC 2355, open cluster, Gemini
92x. Another condensed group of faint stars. Brightest member on southern edge. Curving chain of stars leading north to brighter star. Pretty cluster!

NGC 2395, open cluster, Gemini
92x. Kite-shaped cluster of stars. Sparse, loose; not as good as 2355.

M50, open cluster, Monoceros
92x. As noted previously: rich, large. Prominent red star on southern edge of cluster.

NGC 2335, open cluster, Monoceros
92x. Small, sparse cluster, but there seemed to be an underlying haze of unresolved stars.

NGC 2343, open cluster, Monoceros
92x. Small and sparse again, but brighter stars than 2335. Roughly triangular in shape.

W Canis Majoris, carbon star, Canis Major
92x. Scarlet-hued star; distinctive, but not as vivid as Hind’s Crimson Star.

NGC 2353, open cluster, Monoceros
92x. Rich, if sprawling cluster, gathered around a bright 6th magnitude star (apparently a foreground star rather than a cluster member).

NGC 2362, Tau Canis Majoris cluster (Caldwell 64), Canis Major
92x. In a word: wow! I’ve never seen a cluster quite like this before. A stunning sight in the Ethos despite its very low altitude (declination -25 degrees). A brilliant 4-5 magnitude star (Tau) surrounded by a rich swarm of bright stars. Tau (which apparently is a member and not a foreground star) has a faint companion a few arcseconds east. The cluster has a roughly triangular shape, with another bright star further to the east. It almost looks too good to be true, like it was designed by a VFX artist for a sci-fi film. The highlight of the night.

NGC 2354, open cluster, Canis Major
92x. Loose, filmy mass of stars somewhat washed out by light pollution. Would no doubt be more impressive if it were higher in the sky (and not so near to NGC 2362).

NGC 2360, open cluster, Canis Major
(Caldwell 58) 92x. As previous description. Rich, straggly cluster of moderately bright stars.

NGC 2359, “Thor’s Helmet”, emission nebula, Canis Major
Ethos 13mm + OIII filter. I remember seeing a colour photo of this nebula in an astronomy book when I was a kid, and I was struck by how dramatic it looked: like a spectral demon charging headlong through the heavens. It’s an image that has stayed with me (particularly when I read the epigraph of JG Ballard’s story The Illuminated Man), but I never imagined I would get to see this nebula with my own eyes. For some reason I thought it was only visible from the southern hemisphere (curiously, O’Meara, in his book The Secret Deep, was under the same impression), but while planning my exploration of this part of the sky I realised that not only was its declination just -13 degrees, but also – crucially – it might be bright enough to see in the XT10.

I couldn’t see any nebulosity when I scanned the region unfiltered, but when I added the OIII it was immediately obvious, appearing as a bowl-shaped hemisphere of light with a short bright extension angling away from the southern end (one of the “horns” of the helmet). After staring at it (and to the side of it) for a little while I was able to see the other “horn” as a longer, fainter extension angling from the northern end, pointing west, as well as a bright spot on the northern edge of the bowl. Comparatively, NGC 2359 reminded me of a ghostlier version of the Crescent Nebula (NGC 6888 in Cygnus), another object which responds similarly well to filters, and is itself also powered by a Wolf-Rayet star.

It has to be said that telescopically NGC 2359 looked less like a spectral demon and more like a spectral cauliflower, but as nebulae go it was still very impressive. If NGC 2362 was the night’s highlight, this was a close second.

NGC 2438, planetary nebula, Puppis
With the OIII filter still in place I moved the scope across to NGC 2438, which would arguably be one of the winter’s best planetary nebulae even if it didn't share a telescopic field with M46. The OIII filter dimmed the surrounding starlight, thus making 2438 much more distinct, although it’s nowhere near as bright as the Eskimo Nebula in Gemini. On this occasion it looked a little like M57, appearing as a ring with a darker centre – although the dark core was smaller in size compared to the ring, giving the nebula a more donut-like appearance. Also the nebula seemed larger than it did on 17 January, though this was probably an illusory effect caused by the filter subduing M46.

NGC 2440, planetary nebula, Puppis
Small disc of light a few degrees south of 2438. A field star to the east helps confirm its status; otherwise I think it would be easy to overlook, particularly at low magnification. A close double star to the southeast can also distract the unwary observer. Very bright in the OIII filter; direct vision suggested a bright core and averted vision suggested a faint outer halo, but my eyes were getting very tired by this stage so it was hard to be sure. One to revisit at higher magnification.

Nature note
One frog in the pond (the usual long-stayer), plus lots of wriggling insect larvae.